Multi-threaded chunk saving (not really)

sources/src/main/java/net/minecraft/server/FileIOThread.java

@@ -0,0 +1,81 @@
+package net.minecraft.server;
+
+import java.util.List;
+
+/**
+ * Akarin Changes Note
+ * 1) Multi-threaded chunk saving (performance)
+ */
+public class FileIOThread implements Runnable {
+
+    private static final FileIOThread a = new FileIOThread();
+    private final List<IAsyncChunkSaver> b = /*Collections.synchronizedList(Lists.newArrayList())*/ null; // Akarin - I don't think any plugin rely on this
+    private volatile long c;
+    private volatile long d;
+    private volatile boolean e;
+
+    private FileIOThread() {
+        // Thread thread = new Thread(this, "File IO Thread"); // Akarin
+
+        // thread.setPriority(1); // Akarin
+        // thread.start(); // Akarin
+    }
+
+    public static FileIOThread a() {
+        return FileIOThread.a;
+    }
+
+    public void run() {
+        while (true) {
+            this.c();
+        }
+    }
+
+    private void c() {
+        for (int i = 0; i < this.b.size(); ++i) {
+            IAsyncChunkSaver iasyncchunksaver = (IAsyncChunkSaver) this.b.get(i);
+            boolean flag = iasyncchunksaver.a();
+
+            if (!flag) {
+                this.b.remove(i--);
+                ++this.d;
+            }
+
+            // Paper start - Add toggle
+            if (com.destroystokyo.paper.PaperConfig.enableFileIOThreadSleep) {
+                try {
+                    Thread.sleep(this.e ? 0L : 2L);
+                } catch (InterruptedException interruptedexception) {
+                    interruptedexception.printStackTrace();
+                }
+            }
+            // Paper end
+        }
+
+        if (this.b.isEmpty()) {
+            try {
+                Thread.sleep(25L);
+            } catch (InterruptedException interruptedexception1) {
+                interruptedexception1.printStackTrace();
+            }
+        }
+
+    }
+
+    public void a(IAsyncChunkSaver iasyncchunksaver) {
+        if (!this.b.contains(iasyncchunksaver)) {
+            ++this.c;
+            this.b.add(iasyncchunksaver);
+        }
+    }
+
+    public void b() throws InterruptedException {
+        this.e = true;
+
+        while (this.c != this.d) {
+            Thread.sleep(10L);
+        }
+
+        this.e = false;
+    }
+}